This invention relates generally to the field of vault construction, and more particularly to an improved laminated wall construction forming panels which are interconnected to form an enclosure. Constructions of this general type are known in the art, and the invention lies in specific constructional details which permit the obtaining of improved lightness of weight and lowered cost of construction, without sacrificing resistance to penetration.
In my copending application, Ser. No. 6/325,135, filed Nov. 27, 1981, there is disclosed a panel construction including laminae of steel sheets, plywood, steel mesh, and concrete aggregate having suspended abrasive particles therein.
This construction has proven effective from the standpoint of resistance to penetration by cutting torches, impact hammers, power saws and carbide drills. Tests indicate that the attack time required to penetrate a five layer panel is comparable to that required to penetrate a wall constructed of one-inch thick steel plates plus twelve inches of reinforced concrete block. Similarly, a three layer laminated panel requires an attack time equal to that of a wall formed of three quarter inch thick steel backed by eight inches of reinforced concrete block.
More recently, I have found that other materials offer superior qualities at comparable lesser cost. Oak, particularly red oak, planking, because of the inherent density of the wood has proven superior to plywood. A mixture of vermiculite and cement is easily poured into interstices more readily than concrete aggregate, and tends to be substantially lighter in weight without sacrificing fire resistance. Rather than mix a carbide abrasive into the concrete, it can be applied to epoxy adhesive layers which interconnect the laminae by sprinkling the adhesive layer, thereby reducing the amount of abrasive necessary to be provided, and disposing it in successive layers which come into service as the panel is penetrated.